Thermal insulation concrete and preparation method thereof

Abstract

The invention discloses thermal insulation concrete and a preparation method thereof, and relates to the technical field of lightweight concrete. The preparation method comprises the following steps: firstly, depositing a carbon nano tube through a plasma enhanced chemical vapor deposition method, and optimizing the adhesive force of the carbon nano tube on the surface of basalt fiber; meanwhile, spraying citric acid is introduced and then reacts with urea to generate carbon quantum dots in high-temperature microwaves to form an uneven interface, particles are tightly combined and are not prone to falling off, the heat transfer efficiency is improved, and the heat preservation performance and the mechanical performance are improved; secondly, by utilizing the hydrophobicity of the modified nano silicon dioxide, the foam size is refined, and pores and nodes in a foam concrete net structure are filled; then, the modified basalt fibers, phenolic resin and a foam concrete system are compounded to form a three-dimensional structure, pores are filled, communicating pores before and after hardening are reduced, and the thermal insulation performance and the mechanical performance of foam concrete are both considered. The foam concrete prepared by the invention has the effects of heat preservation, heat insulation and high mechanical property.

Description

Technical Field

[0001] The invention relates to the technical field of lightweight concrete, in particular to thermal insulation concrete and a preparation method thereof. Background Art

[0002] Foamed concrete is a lightweight concrete containing a large number of closed pores formed by pre-preparing foam using physical methods such as rapid mixing or compressed air, and then mixing the foam with cement-based material slurry and curing it. Due to the large number of closed pores inside, foamed concrete has the superior properties of lightness, heat preservation, sound insulation and fire resistance, which can significantly reduce building energy consumption and is an ideal insulation material in the field of civil engineering.

[0003] Although the development of foamed concrete is beneficial to saving resources and protecting the environment, compared with other concretes, foamed concrete has defects such as low strength and easy cracking, which greatly limits the development of foamed concrete. At present, the most common methods to improve the strength of foamed concrete are to adjust the mix ratio of foamed concrete, add coarse aggregates such as ceramsite, and improve the curing conditions. However, when adding coarse aggregates such as ceramsite, if the particle size of the ceramsite is not taken into account, and the ceramsite will be suspended in the upper layer of the foamed concrete due to its too small density, the effect of coarse aggregate on the strength of foamed concrete will be greatly reduced. How to improve the mechanical properties of foamed concrete while ensuring thermal insulation performance is the research direction of this invention. Summary of the invention

[0004] The object of the present invention is to provide a thermal insulation concrete and a preparation method thereof to solve the problems existing in the prior art.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions: a thermal insulation concrete, wherein the concrete is a foamed concrete prepared with modified basalt fiber, phenolic resin, modified nano-silica and cement as main raw materials.

[0006] Furthermore, the modified basalt fiber is a basalt fiber with carbon nanotubes and carbon quantum dots attached to the surface.

[0007] Furthermore, the carbon nanotubes are prepared by plasma enhanced chemical vapor deposition, and the carbon quantum dots are deposited on the surface of the carbon nanotubes by spraying citric acid during chemical deposition and then reacting with the sprayed urea.

[0008] Furthermore, a method for preparing thermal insulation concrete comprises the following preparation steps:

[0009] (1) The basalt fiber was placed in anhydrous ethanol with a solid-liquid ratio of 1:5, and ultrasonically cleaned at a power of 30 kHz for 0.5-2 h, then taken out, washed twice with deionized water, and then dried in an oven at 40°C for 1-3 h; the dried basalt fiber was subjected to plasma enhanced chemical vapor deposition of carbon nanotubes, and the process parameters were: RF power: 400 W, deposition temperature: 500°C, deposition pressure: 350 Pa, methane flow rate: 200-500 sccm, and deposition time of 1-3 h; then the temperature was lowered to 200°C , while depositing, spraying citric acid aqueous solution at a flow rate of 280-460 ml / min for 1-3 min; finishing carbon nanotube deposition and spraying of citric acid aqueous solution, cooling to 80°C, spraying urea aqueous solution at a flow rate of 400-800 ml / min for 1-3 min; finally, microwave heating for 5 min at a power of 600-800 W; washing the microwaved basalt fiber twice with deionized water, and drying in a drying oven at 60°C for 5 h to obtain modified basalt fiber;

[0010] (2) dispersing 1 part of silane coupling agent in 50 parts of anhydrous ethanol, and then stirring and dispersing at a speed of 120 rpm for 10 minutes to prepare a modified solution with a mass fraction of 2%; at room temperature, adding silicon dioxide particles with a particle size of 30 nm according to a solid-liquid ratio of 1:5-10, stirring at a speed of 120 rpm for 20 minutes, and then using an ultrasonic water bath for dispersion treatment for 30 minutes, the ultrasonic power is 40 kHz, and then heated to 80° C. for reaction for 12 hours, and then filtered, taking the filtrate, washing it twice with deionized water, and drying it to obtain modified nano-silica;

[0011] (3) 50-60 parts of silicate cement, 6-14 parts of modified basalt fiber, 2-3.6 parts of modified nano-silicon dioxide and 0.2-0.8 parts of a water reducer are mixed, and stirred at 2000 rpm for 2 min in a high-speed homogenizer to prepare a premix, and then 15 parts of deionized water and 10 parts of sodium dodecyl sulfate are mixed, and stirred at 250 rpm for 10 min to obtain a foam; all the foam is added to the premix, and stirred at 200 rpm for 20 min, and then 1-5 parts of phenolic resin are added, and stirred at 150° C. for 2 h at a stirring speed of 100 rpm. After the stirring is completed, the mixture is cooled to obtain a thermal insulation foam concrete.

[0012] Furthermore, in step (1), the diameter of the basalt fiber is 5 mm.

[0013] Furthermore, the concentration of the citric acid aqueous solution in step (1) is 30%.

[0014] Furthermore, the concentration of the urea aqueous solution in step (1) is 40%.

[0015] Furthermore, the silane coupling agent in step (2) is silane coupling agent KH550.

[0016] Furthermore, the drying process in step (2) is to place the product in a drying oven and dry it at 50° C. for 2 hours.

[0017] Furthermore, in step (3), the water reducing agent is polycarboxylic acid.

[0018] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0019] The invention uses modified basalt fiber, phenolic resin, modified nano silicon dioxide and cement as main raw materials to prepare foam concrete to achieve the effects of thermal insulation and high mechanical properties.

[0020] First, carbon nanotubes are deposited on the surface of basalt fiber by plasma enhanced chemical vapor deposition. The metal elements in the basalt fiber itself act as catalysts to make the carbon nanotubes deposit evenly and orderly, optimizing their adhesion on the surface of basalt fiber. During chemical deposition, spray citric acid is introduced, which then reacts with urea to attach to the carbon nanotubes, and forms carbon quantum dots with carboxyl groups on the surface in high-temperature microwaves as a precursor. Due to their different sizes and different numbers of layers, carbon nanotubes and carbon quantum dots form an uneven interface on the surface of basalt fiber, which effectively reduces the heat release rate of foam concrete, improves the heat transfer efficiency inside the foam concrete, and improves the thermal insulation performance of the foam concrete. In addition, because the active groups in the precursor are firmly combined with the carbon nanotubes and basalt fibers, the dispersion of carbon particles in foam concrete is solved, and the particles are less likely to fall off, further improving the overall mechanical properties of the foam concrete.

[0021] Secondly, nano-silicon dioxide is modified by silane coupling agent to make it hydrophobic, and then added into foam concrete to refine the foam size; however, the foam concrete after adding the mineral has a higher porosity and greater brittleness; the present invention combines the modified basalt fiber and phenolic resin with the foam concrete system to form a three-dimensional structure to improve the overall mechanical properties; the carboxyl groups on the surface of the modified basalt fiber and the hydroxyl groups in the phenolic resin are combined through hydrogen bonds to fill the pores, reduce the connected pores before and after hardening, and significantly improve the strength; at the same time, nano-silicon dioxide can fill the pores and nodes in the network structure of the foam concrete, taking into account the thermal insulation and mechanical properties of the foam concrete. DETAILED DESCRIPTION

[0022] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0023] In order to more clearly illustrate the method provided by the present invention, the following examples are used to describe in detail the various index testing methods of a thermal insulation concrete prepared in the following examples are as follows:

[0024] Thermal conductivity test: The foamed concrete slurry of the embodiment and the comparative example was poured into a mold with a size of 300mm×300mm×30mm, and the mold was removed after curing for 1 day under standard curing conditions. The samples were cured for 28 days under standard curing conditions. The experimental environment temperature was 18-22°C and the relative humidity was 65-75%. The samples were placed in an oven and dried to constant weight at 95°C, and the thermal conductivity of the samples was measured according to GB / T10294.

[0025] Compressive strength: The foamed concrete slurry of the embodiment and the comparative example was poured into a mold with a size of 300mm×300mm×30mm, and was placed under standard curing conditions for 1 day before demolding. The samples were cured under standard curing conditions for 28 days to prepare the samples. The experimental environment temperature was 18-22°C and the relative humidity was 65-75%. The samples were tested for the compressive strength of foamed concrete according to JG / T266-2011 "Foamed Concrete".

[0026] Example 1

[0027] (1) A basalt fiber with a diameter of 5 mm was placed in anhydrous ethanol with a solid-liquid ratio of 1:5. After ultrasonic cleaning at a power of 30 kHz for 0.5 h, it was taken out and washed twice with deionized water, and then dried in an oven at 40°C for 1 h. The dried basalt fiber was subjected to plasma enhanced chemical vapor deposition of carbon nanotubes. The process parameters were: RF power: 400 W, deposition temperature: 500°C, deposition pressure: 350 Pa, methane flow rate: 200 sccm, and deposition time: 1 h. The temperature was then lowered to 200°C. At the same time as deposition, a 30% citric acid aqueous solution was sprayed at a spray flow rate of 280 ml / min for 1 min; after the carbon nanotube deposition and the spraying of the citric acid aqueous solution were finished, the temperature was lowered to 80° C., and then a 40% urea aqueous solution was sprayed at a spray flow rate of 400 ml / min for 1 min; finally, microwave heating was performed for 5 min at a power of 600 W; the microwaved basalt fiber was washed twice with deionized water, and dried in a drying oven at 60° C. for 5 h to obtain a modified basalt fiber;

[0028] (2) Dispersing 1 part of silane coupling agent KH550 in 50 parts of anhydrous ethanol, and then stirring and dispersing at a speed of 120 rpm for 10 minutes to prepare a modified solution with a mass fraction of 2%; at room temperature, adding silica particles with a particle size of 30 nm according to a solid-liquid ratio of 1:5, stirring at a speed of 120 rpm for 20 minutes, and then using an ultrasonic water bath for dispersion treatment for 30 minutes, the ultrasonic power is 40 kHz, and then heated to 80°C for reaction for 12 hours, and then filtered, taking the filtrate, washing it twice with deionized water, and sending it to a drying oven for drying at 50°C for 2 hours to obtain modified nano-silica;

[0029] (3) 50 parts of silicate cement, 6 parts of modified basalt fiber, 2 parts of modified nano-silica and 0.2 parts of polycarboxylate water reducer were mixed, and stirred at 2000 rpm for 2 min in a high-speed homogenizer to prepare a premix, and then 15 parts of deionized water and 10 parts of sodium dodecyl sulfate were mixed, and stirred at 250 rpm for 10 min to obtain a foam; all the foam was added to the premix, stirred at 200 rpm for 20 min, and then 1 part of phenolic resin was added, and stirred at 150° C. for 2 h at a stirring speed of 100 rpm. After cooling after stirring, thermal insulation foam concrete was obtained.

[0030] Example 2

[0031] (1) A basalt fiber with a diameter of 5 mm was placed in anhydrous ethanol with a solid-liquid ratio of 1:5. After ultrasonic cleaning for 1.25 h at a power of 30 kHz, the fiber was taken out and washed twice with deionized water, and then dried in an oven at 40°C for 2 h. The dried basalt fiber was subjected to plasma enhanced chemical vapor deposition of carbon nanotubes. The process parameters were: RF power: 400 W, deposition temperature: 500°C, deposition pressure: 350 Pa, methane flow rate: 350 sccm, and deposition time: 2 h. The temperature was then lowered to 200°C. , while depositing, a 30% citric acid aqueous solution was sprayed at a flow rate of 370 ml / min for 2 min; after the carbon nanotube deposition and the spraying of the citric acid aqueous solution, the temperature was lowered to 80°C, and then a 40% urea aqueous solution was sprayed at a flow rate of 600 ml / min for 2 min; finally, microwave heating was performed for 5 min at a power of 700 W; the microwaved basalt fiber was washed twice with deionized water, and dried in a drying oven at 60°C for 5 h to obtain modified basalt fiber;

[0032] (2) Dispersing 1 part of silane coupling agent KH550 in 50 parts of anhydrous ethanol, and then stirring and dispersing at a speed of 120 rpm for 10 minutes to prepare a modified solution with a mass fraction of 2%; at room temperature, adding silicon dioxide particles with a particle size of 30 nm according to a solid-liquid ratio of 1:7.5, stirring at a speed of 120 rpm for 20 minutes, and then using an ultrasonic water bath for dispersion treatment for 30 minutes, the ultrasonic power is 40 kHz, and then heated to 80°C for reaction for 12 hours, and then filtered, taking the filtrate, washing it twice with deionized water, and sending it to a drying oven for drying at 50°C for 2 hours to obtain modified nano-silica;

[0033] (3) 55 parts of silicate cement, 10 parts of modified basalt fiber, 2.8 parts of modified nano-silica and 0.5 parts of polycarboxylate water reducer were mixed, and stirred at 2000 rpm for 2 min in a high-speed homogenizer to prepare a premix, and then 15 parts of deionized water and 10 parts of sodium dodecyl sulfate were mixed, and stirred at 250 rpm for 10 min to prepare a foam; all the foam was added to the premix, stirred at 200 rpm for 20 min, and then 3 parts of phenolic resin were added, stirred at 150° C. for 2 h at a stirring speed of 100 rpm, and after cooling after stirring, thermal insulation foam concrete was obtained.

[0034] Example 3

[0035] (1) A basalt fiber with a diameter of 5 mm was placed in anhydrous ethanol with a solid-liquid ratio of 1:5. After ultrasonic cleaning at a power of 30 kHz for 2 h, it was taken out and washed twice with deionized water, and then dried in an oven at 40°C for 3 h. The dried basalt fiber was subjected to plasma enhanced chemical vapor deposition of carbon nanotubes. The process parameters were: RF power: 400 W, deposition temperature: 500°C, deposition pressure: 350 Pa, methane flow rate: 500 sccm, and deposition time: 3 h. The temperature was then lowered to 200°C and the deposition was continued. At the same time as the deposition, a 30% citric acid aqueous solution was sprayed at a flow rate of 460 ml / min for 3 min; after the carbon nanotube deposition and the spraying of the citric acid aqueous solution, the temperature was lowered to 80°C, and then a 40% urea aqueous solution was sprayed at a flow rate of 800 ml / min for 3 min; finally, microwave heating was performed for 5 min at a power of 800 W; the microwaved basalt fiber was washed twice with deionized water, and dried in a drying oven at 60°C for 5 h to obtain modified basalt fiber;

[0036] (2) Dispersing 1 part of silane coupling agent KH550 in 50 parts of anhydrous ethanol, and then stirring and dispersing at a speed of 120 rpm for 10 minutes to prepare a modified solution with a mass fraction of 2%; at room temperature, adding silicon dioxide particles with a particle size of 30 nm according to a solid-liquid ratio of 1:10, stirring at a speed of 120 rpm for 20 minutes, and then using an ultrasonic water bath for dispersion treatment for 30 minutes, the ultrasonic power is 40 kHz, and then heated to 80°C for reaction for 12 hours, and then filtered, taking the filtrate, washing it twice with deionized water, and sending it to a drying oven for drying at 50°C for 2 hours to obtain modified nano-silica;

[0037] (3) 60 parts of silicate cement, 14 parts of modified basalt fiber, 3.6 parts of modified nano-silica and 0.8 parts of polycarboxylate water reducer were mixed, and stirred at 2000 rpm for 2 min in a high-speed homogenizer to prepare a premix, and then 15 parts of deionized water and 10 parts of sodium dodecyl sulfate were mixed, and stirred at 250 rpm for 10 min to prepare a foam; all the foam was added to the premix, stirred at 200 rpm for 20 min, and then 5 parts of phenolic resin were added, stirred at 150° C. for 2 h, and the stirring speed was 100 rpm. After cooling after the stirring, thermal insulation foam concrete was obtained.

[0038] Comparative Example 1

[0039] The difference between Comparative Example 1 and Example 2 lies in the difference in step (1), where step (1) is modified as follows: a basalt fiber with a diameter of 5 mm is placed in anhydrous ethanol with a solid-liquid ratio of 1:5, and ultrasonically cleaned for 1.25 h at a power of 30 kHz, then taken out, washed twice with deionized water, and then dried in an oven at 40° C. for 2 h; the dried basalt fiber is modified by spraying a 30% citric acid aqueous solution at a spray flow rate of 370 ml / min for 2 min; after completion, the temperature is lowered to 80° C., and then a 40% urea aqueous solution is sprayed at a spray flow rate of 600 ml / min for 2 min; finally, microwave heating is performed for 5 min at a power of 700 W; the microwaved basalt fiber is washed twice with deionized water, and placed in a drying oven at 60° C. for 5 h to obtain modified basalt fiber; the remaining steps are the same as those in Example 2.

[0040] Comparative Example 2

[0041] The difference between Comparative Example 2 and Example 2 lies in the difference in step (1), where step (1) is modified as follows: a basalt fiber with a diameter of 5 mm is placed in anhydrous ethanol with a solid-liquid ratio of 1:5, and ultrasonically cleaned for 1.25 h at a power of 30 kHz, then taken out, cleaned twice with deionized water, and then dried in an oven at 40° C. for 2 h; the dried basalt fiber is subjected to plasma enhanced chemical vapor deposition of carbon nanotubes, and the process parameters are: RF power: 400 W, deposition temperature: 500° C., deposition pressure: 350 Pa, methane flow rate: 350 sccm, and deposition time: 2 h; after the deposition, the microwaved basalt fiber is cleaned twice with deionized water, and placed in a drying oven at 60° C. for 5 h to obtain a modified basalt fiber; the remaining steps are the same as in Example 2.

[0042] Comparative Example 3

[0043] The difference between Comparative Example 3 and Example 2 is that step (1) is different. Step (1) is changed to: placing a basalt fiber with a diameter of 5 mm in anhydrous ethanol with a solid-liquid ratio of 1:5, ultrasonically cleaning it at a power of 30 kHz for 1.25 h, then taking it out, cleaning it twice with deionized water, and then drying it in an oven at 40° C. for 2 h; plasma-enhanced chemical vapor deposition of carbon nanotubes on the dried basalt fiber, the process parameters are: RF power: 400 W, deposition temperature: 500° C., deposition pressure: 350 Pa, methane flow rate: 350 sccm, The deposition time is 2 hours; after the deposition is completed, the temperature is lowered to 200° C., and a 30% citric acid aqueous solution is sprayed at a spray flow rate of 370 ml / min for 2 minutes; the temperature is lowered to 80° C., and a 40% urea aqueous solution is sprayed at a spray flow rate of 600 ml / min for 2 minutes; finally, microwave heating is performed for 5 minutes at a power of 700 W; the microwaved basalt fiber is washed twice with deionized water, and placed in a drying oven at 60° C. for 5 hours to obtain modified basalt fiber; the remaining steps are the same as those in Example 2.

[0044] Comparative Example 4

[0045] The difference between Comparative Example 4 and Example 2 is that there is no step (2), and step (3) is changed to: 55 parts of silicate cement, 10 parts of modified basalt fiber, 2.8 parts of nano-silicon dioxide with a particle size of 30 nm and 0.5 parts of polycarboxylate water reducer are mixed, and stirred at 2000 rpm for 2 min in a high-speed homogenizer to prepare a premix, and then 15 parts of deionized water and 10 parts of sodium lauryl sulfate are mixed, and stirred at 250 rpm for 10 min to prepare a foam; all the foam is added to the premix, stirred at 200 rpm for 20 min, and then 3 parts of phenolic resin are added, stirred at 150° C. for 2 h, and the stirring speed is 100 rpm. After the stirring is completed, cooling is performed to obtain thermal insulation foam concrete; the remaining steps are the same as in Example 2.

[0046] Comparative Example 5

[0047] The difference between Comparative Example 5 and Example 2 is that step (3) is different. Step (3) is changed to: 55 parts of silicate cement, 10 parts of modified basalt fiber, 2.8 parts of modified nano-silicon dioxide and 0.5 parts of polycarboxylate water reducer are mixed, and stirred at 2000 rpm for 2 min in a high-speed homogenizer to prepare a premix; then 15 parts of deionized water and 10 parts of sodium lauryl sulfate are mixed, and stirred at 250 rpm for 10 min to prepare a foam; all the foam is added to the premix, stirred at 200 rpm for 20 min, and after cooling after stirring, thermal insulation foam concrete is obtained; the remaining steps are the same as Example 2.

[0048] Effect example

[0049] Table 1 below shows the performance analysis results of a thermal insulation concrete using Examples 1 to 3 of the present invention and Comparative Examples 1 to 5.

[0050] Table 1

[0051]

[0052]

[0053] From the comparison of the experimental data of the thermal conductivity of the embodiment and the comparative example, it can be found that the present invention deposits carbon nanotubes on the surface of basalt fiber by plasma enhanced chemical vapor deposition, and the metal elements of the basalt fiber itself serve as a catalyst, so that the carbon nanotubes are deposited uniformly and orderly, and the adhesion of the carbon nanotubes on the surface of the basalt fiber is optimized; during the chemical deposition, citric acid is sprayed and then reacts with urea to combine and adhere to the carbon nanotubes, and forms carbon quantum dots with carboxyl groups on the surface as a precursor in a high-temperature microwave; the carbon nanotubes and the carbon quantum dots form an uneven interface on the surface of the basalt fiber due to their different sizes and different numbers of layers, which effectively reduces the heat release rate of the foam concrete, improves the heat transfer efficiency inside the foam concrete, and improves the thermal insulation performance of the foam concrete. From the comparison of the experimental data of the compressive strength of the embodiment and the comparative example, it can be found that the present invention uses a silane coupling agent to modify nano-silicon dioxide, so that it has hydrophobic properties, and is added to the foam concrete to refine the foam size; but the foam concrete after adding the mineral has a higher porosity and greater brittleness; the present invention combines the above-mentioned modified basalt fiber and phenolic resin with the foam concrete system to form a three-dimensional structure to improve the overall mechanical properties; the carboxyl groups on the surface of the modified basalt fiber and the hydroxyl groups in the phenolic resin are combined through hydrogen bonds to fill the pores, reduce the connected pores before and after hardening, and significantly improve the strength. At the same time, nano-silicon dioxide can fill the pores and nodes in the network structure of foam concrete, taking into account the thermal insulation and mechanical properties of foam concrete. Because the present invention uses the active groups with carbon nanotubes and basalt fibers to be firmly combined together, the dispersion of carbon particles in foam concrete is solved, and the particles are also made less likely to fall off, further improving the overall mechanical properties of foam concrete.

[0054] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations within the meaning and scope of the equivalent elements of the claims be included in the invention. Any marking in a claim should not be considered as limiting the claim to which it relates.

Claims

1. A thermal insulation concrete, characterized in that: The concrete is foamed concrete prepared with modified basalt fiber, phenolic resin, modified nano silicon dioxide and cement as main raw materials.

2. The thermal insulation concrete according to claim 1, characterized in that: The modified basalt fiber is a basalt fiber with carbon nanotubes and carbon quantum dots attached to the surface.

3. The thermal insulation concrete according to claim 2, characterized in that: The carbon nanotubes are prepared by plasma enhanced chemical vapor deposition, and the carbon quantum dots are prepared by spraying citric acid during chemical deposition, reacting with the sprayed urea, and adhering to the surface of the carbon nanotubes.

4. A method for preparing thermal insulation concrete, characterized in that: The method comprises the following preparation steps: (1) The basalt fiber was placed in anhydrous ethanol with a solid-liquid ratio of 1:5, and ultrasonically cleaned at a power of 30 kHz for 0.5-2 h, then taken out, washed twice with deionized water, and then dried in an oven at 40°C for 1-3 h; the dried basalt fiber was subjected to plasma enhanced chemical vapor deposition of carbon nanotubes, and the process parameters were: RF power: 400 W, deposition temperature: 500°C, deposition pressure: 350 Pa, methane flow rate: 200-500 sccm, and deposition time of 1-3 h; then the temperature was lowered to 200°C , while depositing, spraying citric acid aqueous solution at a flow rate of 280-460 ml / min for 1-3 min; finishing carbon nanotube deposition and spraying of citric acid aqueous solution, cooling to 80°C, spraying urea aqueous solution at a flow rate of 400-800 ml / min for 1-3 min; finally, microwave heating for 5 min at a power of 600-800 W; washing the microwaved basalt fiber twice with deionized water, and drying in a drying oven at 60°C for 5 h to obtain modified basalt fiber; (2) dispersing 1 part of silane coupling agent in 50 parts of anhydrous ethanol, and then stirring and dispersing at a speed of 120 rpm for 10 minutes to prepare a modified solution with a mass fraction of 2%; at room temperature, adding silicon dioxide particles with a particle size of 30 nm according to a solid-liquid ratio of 1:5-10, stirring at a speed of 120 rpm for 20 minutes, and then using an ultrasonic water bath for dispersion treatment for 30 minutes, the ultrasonic power is 40 kHz, and then heated to 80° C. for reaction for 12 hours, and then filtered, taking the filtrate, washing it twice with deionized water, and drying it to obtain modified nano-silica; (3) 50-60 parts of silicate cement, 6-14 parts of modified basalt fiber, 2-3.6 parts of modified nano-silicon dioxide and 0.2-0.8 parts of a water reducer are mixed, and stirred at 2000 rpm for 2 minutes in a high-speed homogenizer to prepare a premix, and then 15 parts of deionized water and 10 parts of sodium dodecyl sulfate are mixed, and stirred at 250 rpm for 10 minutes to obtain a foam; all the foam is added to the premix, and stirred at 200 rpm for 20 minutes, and then 1-5 parts of phenolic resin are added, and stirred at 150° C. for 2 hours at a stirring speed of 100 rpm. After the stirring is completed, the mixture is cooled to obtain a thermal insulation foam concrete.

5. The method for preparing thermal insulation concrete according to claim 4, characterized in that: The diameter of the basalt fiber in step (1) is 5 mm.

6. The method for preparing thermal insulation concrete according to claim 4, characterized in that: The concentration of the citric acid aqueous solution in step (1) is 30%.

7. The method for preparing thermal insulation concrete according to claim 4, characterized in that: The concentration of the urea aqueous solution in step (1) is 40%.

8. The method for preparing thermal insulation concrete according to claim 4, characterized in that: The silane coupling agent in the step (2) is silane coupling agent KH550.

9. The method for preparing thermal insulation concrete according to claim 4, characterized in that: The drying process in step (2) is to place the product in a drying oven and dry it at 50° C. for 2 hours.

10. The method for preparing thermal insulation concrete according to claim 4, characterized in that: The water reducing agent in step (3) is polycarboxylic acid.

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